Intestinal or Gut Bacteria and Obesity - A Possible Connection

Yogurt often contains active probiotic bacteria, which may be beneficial for our health. In the near future, we may be able to eat probiotics in foods or supplements that help to prevent obesity.
Yogurt often contains active probiotic bacteria, which may be beneficial for our health. In the near future, we may be able to eat probiotics in foods or supplements that help to prevent obesity. | Source

Obesity and Gut Bacteria

Obesity is a complex condition that may have multiple causes. It's becoming frighteningly common in several parts of the world, including North America. Obesity increases the risk of serious health problems, including heart disease, strokes, osteoarthritis, type 2 diabetes and some types of cancer. The condition can be a serious drain on public health budgets as communities try to treat the problems that it causes.

Scientists have recently discovered that certain gut bacteria may contribute to - or even cause - obesity. Gut bacteria live in our intestine. The majority inhabit our large intestine, or colon (the longest part of the large intestine). Many intestinal bacteria are very helpful to us; some seem to have neutral effects on our lives; and a few are harmful.

The discovery that gut bacteria may affect body weight could have enormous repercussions in the treatment of obesity. In the future it may be possible to manipulate the gut environment and its living contents to help normalize body weight.

The term "gut" usually refers to our small and large intestine, although sometimes the word refers to the entire gastrointestinal or digestive tract.
The term "gut" usually refers to our small and large intestine, although sometimes the word refers to the entire gastrointestinal or digestive tract. | Source

In 2014, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 600 million were obese.

— WHO (World Health Organization)

What is Obesity?

There is a difference between being overweight and being obese. The definition of obesity is usually based on a number called the body mass index, or BMI. The BMI is derived from a person's height and weight. There are online calculators which enable a person to discover their BMI. A link to one of them is provided in the "Useful Links and References" section at the end of this article.

For adults, the significance of the BMI number is as follows.

  • less than 18.5 = underweight
  • 18.5 to 24.9 = normal weight
  • 25.0 to 29.9 = overweight
  • 30.0 or higher = obese

This scale is a helpful indication of a person's weight category, but there are a few problems with using the scale. For example, athletes often have increased muscle mass. This mass will increase their weight and give them a higher BMI than they would normally have. Seniors often lose muscle. This may reduce their weight and BMI, even though they may have an unhealthy amount of fat in their body.

Being obese is not the same as being overweight.
Being obese is not the same as being overweight. | Source

Worldwide obesity has more than doubled since 1980.

— WHO (World Health Organization)

Gut Bacteria and Health

Scientists say that we have about ten times more bacterial cells in our body than human cells. The bacterial cells are smaller than our cells and live on our skin and in body passages that are connected to the outside world, such as the respiratory tract and the gastrointestinal tract.

Intriguing research is showing that some of our gut bacteria affect our lives in important ways. They make vitamins that we use, including vitamin K, break down some of our food, reduce the amount of feces that we make and fight harmful bacteria. Some are thought to boost the activity of our immune system, regulate cholesterol metabolism or reduce inflammation.

The Human Microbiome Project is a major effort to discover and categorize all the microorganisms that live in and on our bodies in health and in disease. Identifying these bacteria may have great practical importance. This is especially true with respect to gut bacteria, since they seem to be so important in our lives.

The Human Microbiome

Bacteria in the Intestine and Weight Gain

Researchers at the Cedars-Sinai Medical Center in California have identified one bacterium that appears to be related to weight gain.

The scientists examined exhaled air samples from 792 people. They found that people who had a high concentration of both methane and hydrogen in their breath had a significantly higher BMI and a significantly higher percentage of body fat than other people. The other people who were tested either had normal breath or exhaled a high concentration of only one of the gases.

Scientists know that most of the methane made in our gut is produced by one particular bacterium - Methanobrevibacter smithii. This bacterium is known to absorb hydrogen made by other bacteria and then use the hydrogen to produce methane. The researchers suggest - but don't yet know - that by taking hydrogen from other bacteria Methanobrevibacter is helping these bacteria to survive better. These other bacteria may then break down more food, giving themselves and us more nutrients. As time passes our increased absorption of nutrients could lead to weight gain.

The researchers are now performing experiments in which Methanobrevibacter is eliminated from the gut with targeted antibiotics. They hope to discover how the removal of the bacterium affects the processing of food in the gut.

Some researchers feel that obesity is not caused simply by poor food choices.
Some researchers feel that obesity is not caused simply by poor food choices. | Source

42 million children under the age of 5 were overweight or obese in 2013.

— WHO (World Health Organization)

A Possible Role of Enterobacter in Weight Gain

Scientists at Shanghai Jiao Tong University in China have discovered that another bacterium may affect obesity. They placed a morbidly obese man on a special diet that was designed to change the composition of his gut flora by altering the gut pH. The diet consisted of whole grains, non-digestible carbohydrates, probiotics and traditional Chinese medicines. The man weighed 175 kg (almost 386 lbs) at the start of the diet. He lost 51 kg (about 112 pounds) during the diet, without exercising.

The researchers found that at the start of the diet Enterobacter was the most abundant bacterium in the man's gut. At the end of the diet (which lasted for twenty-three weeks), Enterobacter was almost undetectable in his gut.

The scientists wanted to determine if the change in the gut flora arose because the man lost weight or if the removal of Enterobacter was at least partly responsible for his weight loss. They fed Enterobacter from the patient's gut to some mice but not to others. All the mice were given a high-fat diet. The mice that had the patient's bacterium in their gut gained significantly more weight than the mice without the bacterium, suggesting that the bacterium can cause weight gain.

Bacteria and Metabolic Syndrome

Gut Bacteria Linked to Obesity and Metabolic Syndrome

More bacteria than Methanobrevibacter and Enterobacter are suspected to play a role in obesity. In fact, researchers at the University of Maryland School of Medicine have identified twenty-six species of bacteria that they suspect are linked to inflammation, obesity and metabolic syndrome.

Metabolic syndrome is a collection of factors that increase a person's risk for cardiovascular disease, strokes and type 2 diabetes. To be diagnosed with metabolic syndrome a person must have at least three of the following conditions.

  • abdominal obesity (a large waistline)
  • high blood pressure
  • high fasting blood sugar (or blood glucose)
  • high blood triglycerides
  • low HDL cholesterol (the good type of cholesterol)

Although they are not part of the criteria for diagnosing metabolic syndrome, a person with the condition often has a high blood level of LDL cholesterol (the bad cholesterol), insulin resistance and widespread inflammation.

The researchers found that the twenty-six bacteria were common in people who were obese or had signs of metabolic syndrome but were much less abundant in healthy people. More studies are needed to discover whether the twenty-six bacteria cause obesity or are present as an effect of obesity.

Abdominal obesity is the most serious type  with respect to health.
Abdominal obesity is the most serious type with respect to health. | Source

Other Bacteria Linked to Obesity

Researchers have discovered that certain bacteria can cause obesity in mice. A group of bacteria called the Firmicutes is associated with obesity and a group known as the Bacteroidetes is associated with weight loss.

Scientists took samples of the intestinal microbiome from obese mice and placed them in the intestine of lean mice. As a result, the lean mice developed extra fat deposits. What is true for mice may not be true for humans, but it often is.

Despite the suspicion that gut bacteria contribute to obesity, the conventional suggestions for losing weight are still important. These include limiting fat and sugar in the diet, including whole grains, vegetables, legumes (pulses) and unsweetened fruits, and exercising for at least 150 minutes a week. Obese and very overweight people should always seek medical advice before starting an exercise program.

What are Probiotics?

The Causes and Potential Treatments of Obesity

While inappropriate food choices and lack of exercise can cause weight gain, there is a growing suspicion that the causes of obesity are more complex. Some researchers believe that obesity is caused or influenced by fundamental changes in the body. One of these changes may be the composition of the intestinal microbiome.

There are two possible reasons for the observed link between gut bacteria and obesity. Specific gut bacteria could be the cause of obesity. On the other hand, obesity may produce conditions that favour the presence of the bacteria.

Research results obtained so far suggest that in at least some cases the presence of specific bacteria contributes to obesity. This is an exciting observation because it could open the door to new treatments for the condition.

Certain bacteria may be able to prevent obesity by destroying harmful bacteria or by keeping their population under control. Other bacteria may change the environment in the gut, making conditions unfavourable for the growth of the harmful bacteria.

"Probiotics" are bacteria and yeasts that are thought to have health benefits. In the future, it may to possible to give people obesity-fighting bacteria in the form of a probiotic supplement. Dietary components may also be used to change the gut environment in a helpful way. Another possibility is that antibiotics may be able to destroy harmful bacteria. Research is ongoing.

Waists are expanding in many parts of the world. It's important that we find an effective solution for this problem.
Waists are expanding in many parts of the world. It's important that we find an effective solution for this problem. | Source

A Healthy Diet and a Good Exercise Routine are Necessary

It's well known that a bad diet and lack of exercise often lead to weight gain. Anybody who is overweight or obese should modify their diet and exercise routine if these need improvement. It would be wonderful if the addition of certain bacteria to the intestine could help the process of weight loss, though. In the near future we will hopefully have new ways to help obese people. Obesity is a problem that we need to solve.

Useful Links and References

Just enter your height and weight into this handy National Heart Lung and Blood Institute calculator and it will quickly display your BMI.

© 2013 Linda Crampton

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Comments 40 comments

billybuc profile image

billybuc 3 years ago from Olympia, WA

Great information, Alicia. Happily I have never had a problem with obesity but this country certainly does. Very interesting facts.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the visit and the comment, Bill. It is scary to see that obesity is becoming more common in so many areas. I hope new solutions are found very soon.


cabmgmnt profile image

cabmgmnt 3 years ago from Northfield, MA

interesting insights, sad to say that antibiotics wipe out good flora in your intestines making the use of probiotics almost necessary for optimal gut health.


wabash annie profile image

wabash annie 3 years ago from Colorado Front Range

Most of us have wondered about what has been causing the obesity 'epidemic'. Often extremely overweight people eat no more/worse than anyone else. Your information is very interesting.


drbj profile image

drbj 3 years ago from south Florida

This is a fascinating subject, Alicia, as our country is becoming obesogenic. I, too, wrote about this subject in my hub, 'Obesity is Widespread.' What a boon to mankind if scientists can discover how to helpfully change our gut bacteria to combat weight gain.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, cabmgmnt. Yes, antibiotic treatment can be very frustrating when it kills good bacteria as well as the bad ones! An interesting development is the appearance of narrow spectrum or targeted antibiotics that kill only certain bacteria. I hope these become more effective at destroying specific bacteria and leaving others unharmed. We certainly need better antibiotics! Thanks for the comment.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, wabash annie. Yes, sometimes obese people are stigmatized for their condition when they aren't doing anything obvious to cause their problem. Even if they are following an unhealthy lifestyle they need help instead of criticism. Thanks for the comment.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks for the visit and the comment, drbj. It would be wonderful if scientists could safely influence the bacterial community in the gut to cure obesity. I hope this wish becomes reality!


LA Elsen profile image

LA Elsen 3 years ago from Chicago, IL

Very interesting and informative. I have no doubt in my mind that there are other factors causing the obesity epidemic. Very enlightening.

Voted up and shared.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the vote and the share, LA Elsen! I'm sure that there's a lot more for us to discover about the causes of obesity. It's a complicated disorder.


wqaindia profile image

wqaindia 3 years ago from Rajpura 140401 Punjab India

You have touched a burning topic and that too with a lot of useful information. Every possible cause of obesity is taken care of. Let the preventive steps and causes are circulated to bigger audience. Voted up and tweeted..


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for such a nice comment and for the vote and tweet, wqaindia! I appreciate your visit. There may be several causes of obesity. It's an interesting and important topic to investigate!


osaeoppongde profile image

osaeoppongde 3 years ago from Chicago, IL

This is great! The gut microbiome is definitely connected to our health and immune system, thanks for the info! I read the other day that there is also a link between circadian rhythm, gut bacteria, and overall health.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, osaeoppongde. Thanks for the comment and for sharing the interesting information!


thebiologyofleah profile image

thebiologyofleah 3 years ago from Massachusetts

Really nice summary of all the research going on in this field of study-thanks for sharing. It makes sense that something as multifactoral as obesity should be treated in a multitude of ways. Looks like this angle may be part of the solution.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you, thebiologyofleah. I hope that gut bacteria are part of the solution. The obesity problem needs to be solved!


b. Malin profile image

b. Malin 3 years ago

Hi Alicia, I'm always Amazed at what I learn from your Hubs...Gut Bacteria, who knew? Of course bottom line, in our Country People do eat too much and DON'T exercise.

Probiotics, could that be the answer, along with a Healthy Diet and Exercise. Anyway, thanks for Educating and sharing.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks for the comment, b. Malin. Yes, a good diet and regular exercise are very important for maintaining a healthy weight! Some people may need extra help, though, which is why I hope the gut bacteria research is successful.


watergeek profile image

watergeek 3 years ago

We're constantly looking for ways to blame weight on anything except our own good diet and exercise. Are they looking at all at the connection between constipation and weight gain? Or individuals misreading body signals and eating instead of drinking water? I wonder if that bacterium's job is to compensate, somehow, for the lack of water in the gut, which causes constipation, which causes a buildup of bacteria in the colon. Methanobrevibactor could be an indicator specie, rather than a cause, per se.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Hi, watergeek. You've raised some very interesting points. Whatever the cause or causes, the obesity problem, or the "obesity epidemic" as some people call it, needs to be solved. Thanks for the visit.


bdegiulio profile image

bdegiulio 3 years ago from Massachusetts

Fascinating article Alicia. Also a little spooky knowing that we have more bacteria cells than human cells in our bodies. But I suppose they serve a function. I am lucky in that I have never had a weight problem! That doesn't mean I won't in the future. I also wonder how the use of antibacterial soaps, lotions, etc. affects all of this. You clearly researched this very well, great job. Voting up and sharing.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much, Bill. I appreciate the comment as well as the vote and the share! Some researchers do say that while it's important to remove harmful germs from our skin after high-risks activities, such as using a restroom, some of us are using too many antibacterial substances.


aviannovice profile image

aviannovice 3 years ago from Stillwater, OK

If this works out, people will become significantly healthier. I like the idea. I have found that since eliminating meat from my diet, for the most part, I have lost weight and kept it off, too.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thanks for the visit and for sharing the information, Deb. I hope that influencing the gut bacteria will make people healthier.


Eiddwen profile image

Eiddwen 3 years ago from Wales

So interesting and very useful Alicia;will benfit many so thank you for sharing.

Eddy.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you, Eddy. Have a good weekend!


Nettlemere profile image

Nettlemere 3 years ago from Burnley, Lancashire, UK

Amazing how much there is left to learn about us! I hadn't heard of the human microbiome project. Lots of interesting facts in this well written and researched article!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment, Nettlemere. I appreciate it! The human microbiome project is ambitious, but I think it's very interesting.


teaches12345 profile image

teaches12345 3 years ago

I can see this truth in our present society. So many people out there are suffering from this. Great hub post, Alicia.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the comment, Dianna. It's very sad that obesity is such a major problem today.


rebeccamealey profile image

rebeccamealey 3 years ago from Northeastern Georgia, USA

Very interesting. I love the way food and nutrition science keeps coming up with new stuff. I haven't heard this theory until now. Thanks for sharing!


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you for the comment, Rebecca. The discoveries made by nutrition scientists certainly are interesting!


Peggy W profile image

Peggy W 3 years ago from Houston, Texas

This is very interesting research Alicia. I hope that they come up with some definitive results in order to properly combat the obesity epidemic. Since the proliferation of antibiotics in foods we eat and over treatment with antibiotics, it makes one wonder if that is a part of the causative factors causing so much obesity today. Naturally there are other causes as well...but good that research is being done in this area. Up, useful and interesting votes.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you very much for the comment and all the votes, Peggy. It's interesting to think about all the possible causes of obesity. It's a complex condition.


Minnetonka Twin profile image

Minnetonka Twin 3 years ago from Minnesota

You did an excellent job researching this topic Alicia. Wouldn't it be wonderful if this research ends in helping obesity. I hit many buttons and voted up on this important hub.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you so much, Linda. I appreciate your comment and all the votes. Yes, it would be wonderful if the research with gut bacteria helps to end obesity. It's such a serious disorder.


Ingenira profile image

Ingenira 3 years ago

I think I am reading the encyclopedia ! But you made it more interesting. :)


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you, Ingenira. I'm glad that the article was more interesting than an encyclopedia article!


Sue Bailey profile image

Sue Bailey 3 years ago from South Yorkshire, UK

Another great hub! I'm in danger of becoming your number one fan.


AliciaC profile image

AliciaC 3 years ago from British Columbia, Canada Author

Thank you so much, Sue! I appreciate all your comments very much!

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